黑麦草、丛枝菌根对番茄Cd吸收、土壤Cd形态的影响

采用大田试验研究了在重金属Cd(5.943 mg·kg~(-1)污染下,黑麦草和丛枝菌根对2个品种番茄("德福mm-8"和"洛贝琪")生长、Cd含量以及对土壤微生物、酶活性、p H和Cd形态的影响.结果表明,黑麦草和丛枝菌根单一或复合处理显著提高了2个品种番茄果实、根、茎、叶和植株总干重,增幅分别为14.1%~38.4%和4.2%~18.3%、20.9%~31.5%和8.4%~10.3%、13.0%~16.8%和3.0%~9.5%、10.7%~16.8%和2.7%~7.6%、14.3%~36.6%和4.5%~16.8%.黑麦草和丛枝菌根单一或复合处理增加了土壤中细菌、真菌、放线菌数量及土壤脲酶、转化酶、磷酸酶、过氧化氢酶活性,且土壤微生物数量及土壤酶活性在不同品种和处理间的差异达到显著性水平(P0.05).与番茄套种黑麦草或接种丛枝菌根提高了土壤p H值,降低了土壤中可交换态(EXC-Cd)、碳酸盐态(CAB-Cd)和铁锰氧化态(Fe-Mn-Cd)和土壤中Cd总量,土壤中Cd总量降幅为16.9%~27.8%.2个番茄品种果实、叶、茎和根中的Cd含量分别显著下降了6.9%~40.9%、5.7%~40.1%、4.6%~34.7%和9.8%~42.4%.Cd主要积累在番茄的叶、根和茎中,果实积累较少.比较供试的2个番茄品种,果实Cd含量和积累量及植株Cd总积累量以"洛贝琪""德福mm-8".     

二氧化钛纳米颗粒对湖滨沼泽土壤氮矿化的影响

二氧化钛纳米颗粒（TiO₂NPs）的广泛应用使其环境释放量不断增加,从而影响到土壤氮的转化过程.然而,目前关于TiO₂NPs对湖滨沼泽土壤氮矿化的影响机制尚不明确.因此,本研究以典型沼泽土壤为研究对象,通过室内培养实验研究不同剂量TiO₂NPs处理（0 mg·kg^-1（CK）、10 mg·kg^-1（A10）、100 mg·kg^-1（A100）、250 mg·kg^-1（A250）、1000 mg·kg^-1（A1000））对土壤理化性质、酶活性和氮矿化过程的影响,探讨TiO₂NPs输入对土壤氮矿化过程影响的内在机制.结果表明：①不同剂量TiO₂NPs处理显著降低了土壤pH和总有机碳（TOC）含量（p<0.05）,A100、A250和A1000处理显著降低了硝态氮（NO₃^--N）含量（p<0.05）.②A250和A1000处理显著抑制了过氧化氢酶活性（p<0.05）;培养7 d,不同剂量TiO₂NPs处理均显著促进了脲酶活性（p<0.05）,抑制了脱氢酶活性（p<0.05）;随着培养时间延长,TiO₂NPs处理对脲酶和脱氢酶活性的抑制作用逐渐减弱,表明TiO₂NPs的负面作用会随时间减弱.③不同剂量TiO₂NPs处理对氨化速率没有显著影响（p>0.05）,A250、A1000处理对硝化和矿化速率有显著抑制作用（p<0.01）.④土壤氮矿化速率与土壤pH、总磷（TP）、NO₃^--N含量呈显著正相关,与脲酶、过氧化氢酶活性呈显著负相关.TiO₂NPs主要通过改变沼泽土壤NO₃^--N含量影响氮矿化过程.本研究可为湖滨湿地保护和TiO₂NPs环境风险评估提供理论依据.     

植物根系质外体溶液的提取方法研究:以多环芳烃为例

根系质外体溶液中多环芳烃(PAHs)的分析对于阐明植物根系PAHs吸收运移机制及阻控意义重大.然而,迄今鲜有便捷成熟的植物根系质外体溶液提取方法的报道.为此,本研究以小麦为材料,菲为PAHs的代表,探究了植物根系质外体溶液的真空渗透离心提取方法.结果表明,小麦根系质外体菲提取量随真空度、真空时间、离心速率、离心时间的增加而增大;小麦根系质外体六磷酸葡萄糖脱氢酶(G6PDH)活性随真空度、真空时间、离心速率、离心时间的增加而升高.依据质外体溶液受原生质污染程度小于1%且尽量提取完全的原则,真空渗透离心提取法的最佳真空度为70 k Pa,最佳真空时间为10 min,最佳离心速率为3 068 r·min-1,最佳离心时间为15 min.研究结果可为污染物的植物根系质外体运输研究提供有效、简便的方法支撑.     

一株高效降解废水有机质耐冷菌的筛选、鉴定及特性研究

利用生物法进行污水处理已被国内外广泛使用,但由于温度影响微生物的生长和繁殖,使其成为生物污水处理效率的限制因子.本研究从污水处理厂活性污泥中分离出5株在低温4℃条件下生长良好的菌株,其中菌株DW1在4℃条件下,96 h时可将初始COD为800 mg·L-1的生活污水有机物去除率高达67.7%.结合菌落形态特征、生理生化特性以及16S r DNA序列分析,将菌株DW1初步鉴定为假单胞菌(Pseudomonas sp.).菌株DW1对COD负荷较高的污水处理效果较好;接种量为3%(体积分数)、p H为7.0时,菌株对污水COD去除率和DHA活性较高.在4℃和25℃条件下,菌株DW1均在96 h对污水COD去除率和DHA活性最高,分别为71.2%、11.35μg·m L·h-1(以TF计)和78.8%、15.11μg·m L-1·h-1(以TF计).     

珠线型载漆酶电纺纤维膜对水中菲的净化性能和机理

采用乳液静电纺丝技术制备珠线型载漆酶电纺纤维膜(以下简称酶膜),实现了漆酶在纤维珠泡中的原位包埋固定。与直线型相比,珠线型酶膜的载酶量提高了1倍,酶活性回收率达78.9%,且戊二醛交联可使酶膜储存和操作稳定性显著增加。将优化后所得酶膜用于水中典型多环芳烃菲的净化,结果表明:与游离漆酶相比,珠线型酶膜对污染物的降解率和去除率均显著增加,对0.01~2.00 mg/L的菲溶液吸附率超过80%,降解率超过72%;而且对pH、温度等环境变化的耐受性能明显增强,这主要归功于漆酶在珠泡中的集中固定和纤维珠泡外壳对漆酶的保护作用。此外,发光细菌毒性试验结果表明,经游离漆酶和珠线型酶膜处理后,不同浓度菲溶液的毒性均有所降低,但经酶膜处理后的菲溶液毒性降低更显著。     

Efficacy of rapeseed residue and eggshell waste on enzyme activity and soil quality in rice paddy

Addition of plant residue into soils improves soil physiochemical properties and its fertility. Rapeseed residue is an emerging N source to paddy soils via rice-rape double-cropping practice. The objective of this study was to evaluate the effects of rapeseed residue and eggshell waste on chemical changes and enzyme activity in the rice paddy soil. The powdered eggshells at 0, 1, 3, and 5% were applied once to 7.0 kg paddy repacked soils in each pot treated with the rapeseed residue or the conventional N, P, and K fertilisers. Eight rice seedlings (Oriza sativa L. cv. Ilmibyeo) (40 days after sowing) were transplanted to the treated each pot. The contents of total C (TC) and N (TN), and organic matter (OM) were significantly increased in soils treated with the rapeseed residue compared to the N, P, and K fertilisers. With the addition of eggshell containing ～92% CaCO₃, a considerable increase of soil pH was observed in soils treated with the rapeseed residue and the N, P, and K fertilisers, compared to the untreated soil. Activities of β-glucosidase, urease, and arylsulfatase enzymes were higher in soils treated with the rapeseed residue than soils treated with the N, P, and K fertilisers. The eggshell additions at 1, 3, and 5% into soils treated with the rapeseed residue increased enzyme activity mainly resulting from N mineralisation, whereas no change in enzyme activity was observed in the soils treated with the NPK fertiliser. The combined use of the rapeseed residue and the eggshells can be beneficial to improve soil environment.     

免耕和秸秆还田对小麦生长期内土壤酶活性的影响

利用中国科学院封丘农业生态实验站保护性耕作定位试验平台,研究全翻耕、常规耕作、免耕、全翻耕+秸秆还田、常规耕作+秸秆还田和免耕+秸秆还田6种耕作方式对小麦生长期内土壤酶活性的影响。结果表明:(1)在小麦整个生育期,土壤碱性磷酸酶、转化酶、脲酶活性表现为免耕处理大于常耕处理,翻耕处理小于常耕处理,有秸秆处理大于无秸秆处理,3种酶活性以免耕+秸秆还田处理为最高,翻耕处理最低。(2)在小麦成熟期,土壤脱氢酶活性表现为免耕处理小于常耕处理,其他生育期土壤脱氢酶活性表现为免耕处理大于常耕处理,有秸秆处理大于无秸秆处理。(3)在小麦不同生育期,各处理土壤酶活性表现出不同的规律性:碱性磷酸酶活性在苗期较低,至孕穗期达到峰值,至成熟期又有所降低;转化酶活性呈现在拔节期大幅升高而后降低的变化趋势;脲酶活性分别在苗期和孕穗期较高;脱氢酶活性在整个生育期一直增加,成熟期达到峰值。(4)4种土壤酶活性之间相关性均达显著水平,聚类分析表明,按照土壤总体酶活性水平可将6个处理划分为3组,酶活性水平最高的为免耕+秸秆还田处理,免耕结合秸秆还田能较好地提升土壤酶活性。     

Effects of Matricaria chamomilla L. on lipid peroxidation,antioxidant enzyme systems,and key liver enzymes in CCl4-treated rats

In this study, we investigated the effects of Matricaria chamomilla L. extract (MCE) on lipid peroxidation, antioxidant enzyme systems, and several liver enzymes in carbon tetrachloride (CCl₄)-treated rats. Rats were divided into five groups. The first group (control group) was fed on standard feed. The rats in the other groups (CCl₄, MCE50, MCE100, and MCE200) were injected intraperitoneally with 0.8?mL?kg^?1 CCl₄. Moreover, rats in the MCE50, MCE100, and MCE200 groups were gavaged with 50?mg?kg^?1, 100?mg?kg^?1, and 200?mg?kg^?1 MCE, respectively. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, whole blood malondialdehyde (MDA) and glutathione (GSH) levels, and erythrocyte superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) activity levels were measured after 14 days of exposure. ALT and AST in the CCl₄ group increased significantly in comparison to the control group (p?4, MCE50, MCE100, and MCE200 groups at different significance levels. In conclusion, the findings suggest that, depending on the dose administered, MCE decreases CCl₄-induced damage and consequent oxidative stress in rats; it affects the antioxidant system positively.     

Spore inhibition-based enzyme substrate assay for monitoring of aflatoxin M1 in milk

A spore germination-based concept and its transformation into a field level prototype for monitoring aflatoxin M₁ (AFM₁) in milk was developed. Initially, 15 strains of Bacillus spp. procured from different culture collection were screened for AFM₁ sensitivity using spot assay and marker strain showing inhibition at 0.5 ppb was selected based upon maximum zone of inhibition. The selected strain B. megaterium 2949 was further screened for different enzymes activities and subsequently its spores were produced to an extent of 73.13% ± 3.197% in newly developed sporulation medium containing beef extract (0.0075% ± 0.0004%), yeast extract (0.015% ± 0.001%), peptone (0.0375% ± 0.0016%), and sodium chloride (0.0375% ± 0.0018%). A spore germination-based concept/ assay was optimized by immobilizing spores in eppendorf with pretreated milk (80°C/15 min) containing germinant and chromogenic substrate followed by incubation at 37°C. The appearance of sky blue color within real time of 45 min indicated spores germination and release of specific marker enzyme such as acetyl esterase and its specific action on chromogenic substrate which demonstrates absence of AFM₁ in milk. However, if there was no color change, presence of AFM₁ at 0.5 ppb MRL was denoted by Codex. The developed concept on AFM₁ detection was validated and a correlation of 0.97 was established with AOAC approved Charm 6602 and ELISA at Codex MRL with minimal false positive and negative results. The cost effective test has potential application in dairy farms, manufacturing, and R&D units for routine monitoring of AFM₁ in milk.     

Analysis of the toxicity of glyphosate and Faena® using the freshwater invertebrates Daphnia magna and Lecane quadridentata

With the present contribution an evaluation of the toxicity of the pure herbicide glyphosate and its commercial formulation Faena® is reported using the cladoceran Daphnia magna Strauss and the rotifer Lecane quadridentata Ehrenberg. LC₅₀, EC₅₀, NOEC, and LOEC values for each toxicant and for both test organisms are obtained. Regarding acute toxicity, Faena was 11-fold more toxic to L. quadridentata than pure glyphosate and slightly more toxic to D. magna (1.7-fold). Inhibition of esterase activity in L. quadridentata by glyphosate was the most sensitive end-point; the EC₅₀ was 1500-fold smaller than the LC₅₀. The implications of these results and their comparison with established international and national limit values for glyphosate are discussed.